Respectfully, you are mistaken in this case. ORSV, CymMV and OFV all become systemic in Cymbidiums between 7 and 24 months (at the most), so they most definitely do go "backwards" through the plant.MrCym wrote: ↑Tue Apr 23, 2024 8:46 am But a little tip for an enthusiast who finds a large plant suddenly expressing clear viral symptoms from say a dirty pot or an unsterilized wire stake. In my scientific experience, viruses don’t seem to go backwards. On the rare occasion where l spot a recent infection, l can almost guarantee the oldest bulb(s) are clean! Now, you have to flame your cutting shears or dip them in a 20% solution of Sodium Hypochlorite with every cut but the effort is usually rewarded with a totally clean restart!
Now, you might only see symptoms on the newest growths (particularly in the case of OFV and by that point it's often systemic), but there is no guarantee that the oldest bulbs (despite a lack of symptoms) are not already infected with a low level of virus. If you manage to catch the infection before it becomes systemic, then yes, you could theoretically save the uninfected part of the plant. But you'd need to test it, isolate it, and then re-test at 12 and 24 months to be certain you were successful.
As I said before, all three viruses can be asyptomatic in good culture. It is when the plant is stressed in some way that the symptoms then show up. By this point, it is almost certainly too late and the infection is systemic.